1. Field of the Invention
The present invention relates to an apparatus and method for allocating resources in a mobile communication system.
2. Description of the Related Art
One of the important issues considered in next generation mobile communication systems is which multiplexing technique will be selected to effectively allocate limited resources (i.e., frequency, time, and space) to users. This is because a Quality of Service (QoS) depends on the multiplexing technique.
The recently emerging Orthogonal Frequency Division Multiplex Access (OFDMA) scheme is basically the same as the Frequency Division Multiplex Access (FDMA) scheme except that, in the OFDMA scheme, advantageously, all users can share a Fast Fourier Transform (FFT) space in downlink transmission and sub-carriers can be allocated to the users according to a user data-transfer rate.
However, according to the principle of frequency orthogonality, two users cannot share one sub-channel in the OFDMA scheme. Therefore, as the number of users increases, it becomes more difficult to allocate resources to the users, resulting in unsatisfactory QoS. In addition, even if there is no interference between users in the OFDMA, it is likely that a user located in a cell boundary area cannot receive satisfactory QoS since interference caused by adjacent cells is high. In other words, the OFDMA scheme is limited because, when the number of users increases, resource allocation becomes complicated and frequency usage efficiency decreases.
In the next generation wireless mobile communication system in which a variety of multimedia services are required, there is a need to maintain a suitable QoS of each service and to improve a data transfer rate. In particular, the wireless mobile communication system has to support both a real time based service and a non-real time based service. Therefore, as a greater number of users want to receive services on a real time basis, there has been a problem in that maintenance of QoS becomes further difficult, and frequency efficiency decreases.